Submitted in January, 2002
Revised Location of the Source of The Mekong River, Qinghai, China
Pete Winn, Science Director, Earth Science Expeditions
In the July 1995 issue of Geographic Journal (Vol. 161, Part 2), Michel Peissel reports that the true source of the Mekong River is a spring located at 93 52.929 E and 33 16.534 N on the east slope of Rupsa Pass, based on a September, 1994 expedition. This spring discharges into the Zanaqu, a large tributary flowing east into the Za Qu. The Za Qu joins the Ngom Qu near Qamdo, Tibet to form the Mekong (called the Lancang Jiang in China).
In May, 2001, Zhou Changjin and Guan Zhihua of the Institute of Geographic Sciences and Natural Resources Research the Chinese Academy of Sciences (CAS) published an article identifying a glacial spring located at 94 41 44 E and 33 42 31 N on the north slope of Mt. Guozongmucha as the true geographical source. This spring discharges into the Zayaqu, a large tributary flowing south to join the Zanaqu at Ganasongduo (Reconfirmation on Identification of the True Source and Headwater of Lancang Jiang (Mekong River), Geographical Research, Vol. 20, No.2).
The springs identified by both parties lie in the province of Qinghai, China. The CAS is the official survey agency for the Chinese government and has the authority to make the final determination of the location of the source. Zhou and Guan have reviewed Mr. Peissel's claims and have determined that he did not identify the true source of the Mekong.
By international geographic convention, the geographic source of a river is the spring which is furthest from the mouth of the river. According to measurements using satellite photos, it is nearly five kilometers further from the spring at the source of the Zayaqu to Ganasongduo than it is from the spring identified by Peissel in the Zanaqu drainage.
Mr. Peissel used a 1:500,000 scale tactical pilot chart (TPC) to determine that the Zanaqu was longer than the Zayaqu, went up the Zanaqu to the spring at the furthest point from the confluence, used GPS to determine the location and claimed this spring was the source. TPCs are designed to identify mountain peaks and are not suitable for identifying river sources. Satellite photos and more detailed topographic maps were available at the time.
While Mr. Peissel was traveling up the Zanaqu in September 1994, a Japanese team hosted by Zhou Changjin of CAS was traveling up the Zayaqu. The Japanese team was led by Masayuki Kitamura of Tokyo Agricultural University, using 1:100,000 scale topographic maps obtained from CISNR/CAS. It is evident on these maps that the Zayaqu is longer than the Zanaqu and has a larger and higher drainage area. Using GPS, they determined that the location of the source of the Mekong was 94 41 37 E, 33 43 41 N. The 1994 Sino-Japanese location is about 62 meters lower than and 360 meters north of the location reported by CAS in 2001. This difference can be attributed to glacial retreat and improvements in GPS precision.
In early 1999, Earth Science Expeditions (ESE), an American whitewater rafting organization led by Pete Winn, began planning an expedition to the source of the Mekong identified by Mr. Peissel, unaware that there was a divided opinion as to the location of the source. ESE was using 1:200,000 scale Russian topographic maps to plan its route. These maps had been obtained by many major universities in North America and Europe in early 1994. On these maps it was evident that the Zayaqu was longer than the Zanaqu and had a larger and higher drainage basin.
ESE contacted CAS to determine if their 1:100,000 scale maps supported Mr. Peissel's claim or if in fact the source was the Zayaqu as indicated on the Russian maps. This precipitated a decision by CAS to utilize satellite photos to resolve the discrepancy. Based on the results of their research, CISNR/CAS confirmed that the spring on the north side of Mt. Guozongmucha was the true source of the Mekong. In July 1999, Zhou Changjin again traveled to the Mekong headwaters area to remeasure the location of this spring using GPS.
Translations of reports published by Zhou and others of CAS, maps and other references on the history of the search for the source of the Mekong are available in the Library of the Geographical Journal and online at http://www.shangri-la-river-expeditions.com/mekong/mekongsource/mekongsource.html. CAS publications were obtained and translated into English by Tamotsu Nakamura.